On 1/23/19 8:12 PM, Bart Van Assche wrote:
Since the READ(6) and WRITE(6) commands interpret a zero in the transfer
length field in the CDB as 256 logical blocks, avoid submitting such
commands.

Cc: Douglas Gilbert <[email protected]>
Cc: Hannes Reinecke <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Reported-by: Douglas Gilbert <[email protected]>
Signed-off-by: Bart Van Assche <[email protected]>
---
  drivers/scsi/sd.c | 4 ++++
  1 file changed, 4 insertions(+)

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 4e69f182a1e5..b0eb83526c54 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -1129,6 +1129,10 @@ static blk_status_t sd_setup_rw6_cmnd(struct scsi_cmnd 
*cmd, bool write,
                                      sector_t lba, unsigned int nr_blocks,
                                      unsigned char flags)
  {
+       /* Avoid that 0 blocks gets translated into 256 blocks. */
+       if (WARN_ON_ONCE(nr_blocks == 0))
+               return BLK_STS_IOERR;
+
        if (unlikely(flags & 0x8)) {
                /*
                 * This happens only if this drive failed 10byte rw

Reviewed-by: Hannes Reinecke <[email protected]>

Cheers,

Hannes

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